The author posits a fascinating explanation for the origin of art and the creation of images by early mankind: the evolution of the human mind. He theorizes that the people of the Upper Paleolithic harnessed altered states of consciousness to fashion their society and used imagery as a means of establishing and defining social relationships. Cro-Magnon man had a more advanced neurological system and order of consciousness than the Neanderthals, and experienced shamanic trances and vivid mental imagery. It was important for them to paint these images on cave walls that served as a membrane between the everyday world and the realm of the spirit. Hallucinations were instrumental in personal advancement and the development of society. He refers to the pioneering psychologist William James who already in 1902 pointed out the different states of consciousness and to Colin Martindale who identified the following different states: Waking, realistic fantasy, autistic fantasy, reverie, hypnagogic and dreaming. The sense of absolute unitary being (transcendence/ecstasy ) is generated by a spillover between neural circuits in the brain caused by factors like meditation, rhythmic stimulus, fasting etc. The essential elements of the religious experience are thus wired into the brain. Two case studies are used in support of this theory: South African San rock art and North American rock art. Chapter 8 is especially fascinating since it offers possible solutions to certain puzzles of cave art, like the mixture of representational and geometric imagery. The author believes that the trail of images from the cave entrance to the dark, almost inaccessible recesses represents a connecting link beween the two elements of an "above/below" binary opposition. Physical entry into the caves reflected the entry into the mental vortex that leads to the hallucinations of the deep trance state. In other words, the trail from the conscious mind to the deep recesses of the subconscious. This book provides much food for thought about our earliest ancestors and about the evolution of consciousness. I would like to recommend William James' "The Varieties of Religious Experience," R M Bucke's "Cosmic Consciousness" and Rupert Sheldrake's "Chaos, Creativity and Cosmic Consciousness" as companion reading to Lewis-Williams' fascinating text. The book includes many figures and 97 illustrations of which 27 are in colour.